Which of the following is one of the early signs of lung cancer?

Coughing up blood, also known as hemoptysis, is recognized as one of the early signs of lung cancer. This symptom can occur due to tumor growth or irritation within the lungs, causing damage to blood vessels and leading to the presence of blood in the sputum. It is an important symptom to monitor, as early detection can significantly impact treatment outcomes.

While chronic wheezing, chest pain, and shortness of breath can also be associated with lung cancer or other respiratory diseases, they may not present as early in the disease process compared to hemoptysis. Coughing up blood tends to be a more specific indicator pointing towards possible malignancy and warrants immediate medical evaluation.